Patent GB-369953-A (GB)
Title: Improvements in or relating to filtering systems
IPC: B01D35/14
Filed: 1930-09-19
Abstract: 369,953. Filters; valves. WHITE, A. E., 5, Quality Court, Chancery Lane, London.-(Motor Improvements, Inc. ; 365, Frelinghuysen Avenue, Newark, New Jersey, U.S.A.) Sept. 19, 1930, No. 28020. [Class 46.] The pressure of the liquid flow opens the inlet valve of a filter and compresses a body of air or other gas, which, on cessation of normal flow, causes a reverse cleansing flow through the filter, the reverse flow being automatically limited by valve or like means. The arrangement is described as adapted for filtering the lubricating oil of an internal-combustion engine or oil supplied to a burner. The liquid supplied to the apparatus shown in Fig. 1 pushes the valve 132 back against the resistance of the spring 133, so that the liquid can flow through a passage 127 to a chamber 126 and raise a piston 130 therein. When the piston is raised sufficiently, the liquid passes through an aperture 128 into the space surrounding a filter element 16. As shown the element comprises a ribbed metal ribbon 18 wound helically to form a cylinder which is held between an upper cap 19 and a cup 121. The element is held in position by a clamping member 14 which screws on to a central pipe 12, the lower end of which screws into the base 10. The clamping member also serves to hold the outer casing 11 against the base. The filter element is supported internally by a fluted drum 17, the base 20 of which has a central aperture 20a loosely surrounding the pipe 12. The filtered liquid passes down the flutings of the drum to the cup 121 and thence through an aperture 123 into the pipe 12 and away by an outlet passage 124. The head on the discharge causes liquid to rise within the drum 17 and compresses air therein. With cessation of the liquid supply the valve 132 closes and the compressed air causes a reverse flow, liquid passing through the passage 127 to a waste passage 137. Reverse flow is limited as it ceases when the piston 130 falls below the aperture 128. The waste passage 137 is closed during normal flow but excessive supply pressure overcomes the resistance of a second spring 134 surrounding a rod 136 and engaging the valve 132 so that the valve moves to open the passage 137. There is also a byepass controlled by a spring-loaded valve 39 between the passages 127, 124. In the modified arrangement shown in Fig. 5 the cylinder 126 is omitted, and the reverse flow is limited by the valve 132 which has a cylindrical skirt with apertures which coincide with the openings for the passages 127, 137 for only a limited period during the backward movement of the valve. To facilitate the movement of the valve 132 the end of the rod 136 is provided with a small byepass bore 40. Fig. 7 shows diagrammatically an arrangement in which oil is cleansed by a filter U as it is transferred by a pump P from a tank T to a burner Z. Air, compressed in a dome D during normal flow, causes a reverse cleansing flow of liquid to enter the filter through a restricted passage O when the pump P is stopped, a check valve V then closing the connection between the dome and the burner. A byepass controlled by a relief valve is provided round the pump.